DDC112YSLASH2K datasheet(16/34 Pages) TI

16 / 34 page

DDC112

SBAS085B

www.ti.com

FIGURE 13. Non-Continuous Mode Timing.

Ncont Mode

Figure 13 illustrates operation in the ncont mode. The

integrations come in pairs (that is, sides A/B or sides B/A)

followed by a time during which no integrations occur.

During that time, the previous integrations are being mea-

sured, reset and auto-zeroed. Before the DDC112 can

advance to states 3 or 6, both sides A and B must be

finished with the m/r/az cycle which takes time t10. When the

m/r/az cycles are completed, time t11 is needed to prepare

the next side for integration. This time is required for the

ncont mode because the m/r/az cycle of the ncont mode is

slightly different from that of the cont mode. After the first

integration ends, DVALID goes LOW in time t8. This is the

same time as in the cont mode. The second data will be

ready in time t9 after the first data is ready. One result of the

naming convention used in this application bulletin is that

when the DDC112 is operating in the

ncont mode, it passes

through both

ncont mode states and cont mode states. For

example, in Figure 13, the state pattern is 3, 4, 1, 2, 3, 4, 1,

2, 3, 4...where 3 and 4 are cont mode states.

Ncont mode

by definition means that for some portion of the time, neither

side A nor B is integrating. States that perform an integration

are labeled

cont mode states while those that do not are

called

ncont mode states. Since integrations are performed

in the ncont mode, just not continuously, some cont mode

states must be used in an ncont mode state pattern.

SYMBOL

DESCRIPTION

VALUE (CLK = 10MHz)

VALUE (CLK = 15MHz)

1st ncont mode data ready.

421.2

±0.3µs

280.8

±0.2µs

2nd ncont mode data ready.

454.8

µs

303.2

µs

t10

Ncont mode m/r/az cycle.

910.8

µs

607.2

µs

t11

Prepare side for integration.

≥ 24.0µs

Int B

Int A

Int B

Int A

m/r/az B

m/r/az A

m/r/az B

CONV

State

mbsy

m/r/az

Status

Integration

Status

DVALID

Side A

Data

Side B

Data

Side A

Data

Side B

Data

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